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Amperecalc

Solar & storage

What will a balcony solar system do for you?

A plug-in solar device only saves the money it actually displaces inside your home. This calculator therefore simulates not just generation, but how much of it really lands given the way you use electricity.

How we calculate

Calculation model

  1. 01

    Your postcode maps to an irradiation region with a measured annual global irradiation sum.

  2. 02

    Orientation and tilt are transposed onto the module plane with an anisotropic sky model.

  3. 03

    System losses (temperature, wiring, soiling, inverter) are accounted for individually; the 800 W limit is calculated separately as a clipping loss.

  4. 04

    Generation and your load profile are overlaid hour by hour — only the intersection counts as self-consumption.

Good to know

  • Since the first solar package, 800 W of inverter output and up to 2,000 Wp of module power are permitted.
  • Registration is a simplified entry in the market master data register; separate registration with the grid operator is no longer required.
  • Surplus from plug-in devices is normally not remunerated — it flows into the grid free of charge.

Law & subsidies

What applies in Germany

Regulation determines the limits and tariffs this calculator works with.

800 watts of inverter, 2,000 watt-peak of modules

Plug-in solar devices may run up to 800 W of inverter AC output; installed module power may reach 2,000 Wp.

Inverter
max. 800 W AC
Modules
max. 2,000 Wp DC
Oversizing
Permitted, up to 2.5:1
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The first solar package raised the former 600 W limit to 800 W. What counts is the inverter's output, not the module power — which is why oversizing is explicitly allowed and sensible in practice, since rated power is reached in only a handful of hours per year.

The limit applies per metering point, not per device. Running two devices means their combined output must stay within 800 W.

One registration, not two

Registration is a single entry in the market master data register, due within one month of commissioning. Registration with the grid operator has been abolished.

Deadline
1 month after commissioning
Grid operator
no longer required
Cost
none
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The register now asks plug-in devices for only a few items: location, commissioning date, module and inverter power, and the meter number. The grid operator is notified automatically.

Commissioning means the first time the system generated and exported electricity — not the purchase, and not the mounting.

An old meter may keep running backwards for now

A Ferraris meter without a backstop may stay in place until the metering operator replaces it during the smart meter rollout.

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The meter used to have to be swapped before the system could run. That requirement is gone: you need to arrange nothing and pay nothing.

Until the swap, the backwards-turned share is effectively credited at the household electricity price — an advantage that ends with the new meter, so do not build it into your calculation.

Landlords and owners' associations can no longer refuse outright

Plug-in solar counts as a privileged structural alteration. Others may have a say in how it is installed, not whether.

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Since the reform of tenancy and condominium law there is an entitlement to consent. Landlords and associations may decide on the fixing method and appearance, but may not refuse the installation as such.

There is no entitlement to a particular mounting method. Obtain consent in writing and document the fixing. Above the fall edge, proof of structural stability is sensible.

Zero VAT and income tax exemption up to 30 kWp

Supply and installation of PV systems up to 30 kWp on residential buildings carry no VAT, and the income is exempt from income tax.

VAT
0 % up to 30 kWp
Income tax
exempt up to 30 kWp
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The zero rate covers modules, inverter, storage and installation. You pay the net price without needing to reclaim input tax — the old optimisation via standard taxation is obsolete.

The income tax exemption applies per taxpayer for up to 100 kWp in total and usually removes the need for a trade registration.

This compilation is orientation, not legal advice. Rules in this field change several times a year — check the linked primary source before you invest, or ask a certified specialist.
See all regulatory topics

Frequent questions

Answered briefly.

Is a second module worth it if the inverter caps at 800 W?

Usually yes. Rated power is only reached in a handful of hours per year. Oversizing to roughly 1,000–1,200 Wp costs a few percent in clipping but lifts the yield noticeably on overcast days and in the morning and evening.

South or east/west — which is better?

For raw annual yield, south wins. For savings, east or west often wins, because generation is spread more evenly across the day and matches morning and evening consumption better. The calculator shows both figures separately.

Why is my yield lower on a vertical railing?

At 90° tilt the summer sun strikes the module at a very shallow angle. Across the year that costs roughly 25 to 30 percent against an optimally angled mount. In winter, vertical mounting is actually at an advantage.

Payback calculator

Net present value, internal rate of return and break-even for any energy investment.

Consumption audit

Consumption broken down appliance by appliance — with savings in euros.

Rooftop PV calculator

Yield, self-sufficiency and return of a rooftop array over 25 years.

All results are model calculations based on your inputs and statistical reference data. They do not replace individual professional planning.

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